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Okuma LB15 stuck chuck on spindle taper

BodoW

Plastic
Joined
Mar 25, 2023
Location
Metro Vancouver, B.C. Canada
Hello all,
we've recently got an Okuma LB15 CNC-Lathe but unfortunately the previous owners heard about maintenance
and service only from hear-saying.
I'm disassembling the machine now to clean, maintain and paint the covers and I'm stuck now with a stuck
chuck on the spindle taper. The chuck might not got off the spindle for maybe 20 yrs.

I've made a tool to turn the drawtube and I could loosen the drawtube. The bolts which hold the chuck on the spindle are out too, but the
chuck doesn't wanna get off the taper.
I've tried today to heat up the chuck but it didn't work. Heating and hitting with a big mallet didn't work.
I thought I could use the hydraulic to push the drawtube to the chuck so it might get loose.
The chuck is closed now for OD-gripping. If I would open the chuck the drawtube would move towards the chuck und push it off the taper.
Might work but my concern is that I've already unthreaded the drawtube and when I use the hydraulic the Threads on the tube and in the hydraulic cylinder will get damaged.
What's your opinion for that?
I've tried to turn the drawtube back in but there is maybe too much dirt in it so I can only turn it a bit and then it's tight.
Maybe a 1/4 rev in each direction works but not more.
Would it be a possible solution to remove the hydraulic cylinder, clean the threads from the tube and in the cylinder, assemble it back and using the hydraulic to press the chuck off?

Bodo
 
Hello all,
we've recently got an Okuma LB15 CNC-Lathe but unfortunately the previous owners heard about maintenance
and service only from hear-saying.
I'm disassembling the machine now to clean, maintain and paint the covers and I'm stuck now with a stuck
chuck on the spindle taper. The chuck might not got off the spindle for maybe 20 yrs.

I've made a tool to turn the drawtube and I could loosen the drawtube. The bolts which hold the chuck on the spindle are out too, but the
chuck doesn't wanna get off the taper.
I've tried today to heat up the chuck but it didn't work. Heating and hitting with a big mallet didn't work.
I thought I could use the hydraulic to push the drawtube to the chuck so it might get loose.
The chuck is closed now for OD-gripping. If I would open the chuck the drawtube would move towards the chuck und push it off the taper.
Might work but my concern is that I've already unthreaded the drawtube and when I use the hydraulic the Threads on the tube and in the hydraulic cylinder will get damaged.
What's your opinion for that?
I've tried to turn the drawtube back in but there is maybe too much dirt in it so I can only turn it a bit and then it's tight.
Maybe a 1/4 rev in each direction works but not more.
Would it be a possible solution to remove the hydraulic cylinder, clean the threads from the tube and in the cylinder, assemble it back and using the hydraulic to press the chuck off?

Bodo
The method of using the Draw Tube to push the chuck loose normally works, but you need to screw the draw tube back to being fully engaged with the chuck; there will still be enough forward motion left to dislodge the chuck.Don't try using the hydraulic with the draw tube only engaged by a few threads, as the potential to damage the Threaded Socket in the chuck and the Draw Tube will be high.

Put the bolts that secure the chuck to the spindle back in until they just start to nip up, then back each out an equal amount of say 1-2 turns. The chuck only has to move a few thou to release completely from the taper. If the chuck doesn't let go just with the hydraulic pressure, apply some heat with a hot air gun and when good and hot, strike the backing plate area a sharp blow this plastic. dead blow hammer, or a solid piece of timber applied to the backing plate area and strike a blow with a block hammer.

Regards,

Bill
 








 
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